var Singleton = function (name) {
    this.name = name;
};

Singleton.prototype.getName = function () {
    console.log(this.name);
};

Singleton.getInstance = (function () {
    var instance = null;
    return function (name) {
        if(!instance){
            instance = new Singleton(name);
        }
        return instance;
    };
})();

var a = Singleton.getInstance('sven1');
var b = Singleton.getInstance('sven2');

console.log(a);
console.log(b);

console.log(a===b);